Recoil-pawl



K. s. CARLSTROML RECOIL PAWL.

APPLICATION FILED JUNE B.191a.'

Patented Apr. 26, 1921.

2 SHEETSSHEET 1.

UNITED STATES PATENT oF- ic-E.

Know 5. CABLSTROM, or WALT-HAM, MA S C USETTS, 'Assie voaor 01 3- ALF To JOSEPH n. srunnonmnor WALrrn M, MASSACHUSETTS.

REGOIL-PAWL.

Application file d J' une'8, 1918. Serial No. 238,838.

To all whom it may concern:

is simple in construction, inexpenslve t0 manufacture, and which will effectively prevent the winding mechanism from turning backward, but will give the desired amount of recoil after the winding stem or winding key isreleased.

My improved stop pawl is carried. by and frictionally associated with one of the intermeshing wheels of the winding mechanism, and is provided with i a Stop finger adapted to engage the intermeshing teeth of said wheels thus toprevent backward rotation'thereof. The stop member is permitted to have only a limited turning move ment in a forward direction andthe frictional connection between the stop member and the wheel which carries it is sufficient so that the turning movement of the wheel will give turning movement to the stop member. Hence when the wheels are being turned forwardly to wind up the main spring the stop member will be moved forwardly out of locking engagement with the intermeshing teeth of said wheels thus permitting the winding mechanism to beoperated while when the winding stem or winding key is released, the tension of the main "spring will tend to turn the wheels backwardly, thus turning the stop member backwardly'unt'il the stop' finger thereon comes into engagement'with the intermeshingteeth of said wheels. The stop'finger will thus lock the wheels from furtherbackward rotation. The stop member is inexpensive to manufacture and can be readily appliedto any winding mechanism.

When the invention isused' in connection with the winding mechanism of watches 1 'findit convenient to associate the stop member with the crown wheel but it might be assoclated' with some other wheel without departing from the invention.

In order togive an understanding of my lnvention, I have illustrated in the draw p ion f L r nt- Patented Apr. 26, 1921.

ings a selected embodiment thereof which 1 will now-be described, after which the novel features will be pointed out in the appended claims.

Figure 1 is a view of a portion of a watch movement showing my improved stop mechamsm; Figs. 2. and 3 are enlarged views showing the operation of the stop member;

Fig. 4 is an under side view of the crown wheel with the stop member attached thereto; I i

Fig. 5 is :a side view of Fig. 4:; 1

Fig. 6 shows a modifiedform of the invention 7 is a section on the line 77 Fig. 6; Figs. 8 and 10. show further modifications of the invention;

Fig. 9 is a side view of the stop member shown in Fig. 8;

F1 11 is a perspective view of the stop mem er 24; 1

Fig. 12 shows an embodiment of the in-" vention wherein the stop'member is associated with the ratchet wheel 6. 1

1 indicates a portion of a watch casing having the usual winding stem 2 by which the main spring" (not shown) is wound.

Thislwinding stem 2 is usually provided with a pinionwhich meshes with the teeth 30f the crown wheel 4, the latter having "teeth 5 on itsperiphery which mesh with the usualratchet wheel '6 of the winding mechanlsm. The crown wheel 4 and ratchet wheel 6 are situated in recesses 7 and 8 formed in' the plate 9 of the .watchmovement and are secured to. said plate by suitable screws 10 andu11- which constitute the arbors; about which they rotate.

' y improved stop member or. stop pawlis associated and has frictional contact with either the crown wheel 4 or the ratchet. wheel .6. I will preferably employ a stop member constructed tobe mountedon and have; frictional engagement with the crown wheel 1,

and this is the construction shown in the drawlngs. The stop member shown in Figs. 1 to 5 is in the form of an annular platelike member 12 adapted to fit over the hub 13 of the crown wheel, said member having an exterior diameter slightly less than the tooth portion 5 of the crown wheel. This annular member 12 has a stop finger 1 f eX- tending therefrom which is provided with an upturned portion 15 which is situated in the plane of the teeth 5 and just outside of the latter. This stop member 12 is made quite thin and takes up no appreciable room. It has sufficient frictional engagement with the crown wheel so that if left free and unrestrained it will rotate therewith.

The position of the stop finger 15 adjacent the end of the teeth 5 is such that when the winding of the main spring ceases and the ratchet wheel and crown wheel tend to turn backwardly due to the tension of the wound main spring, the frictional engagement between the stop member and the crown wheel will cause the stop member to turn with the crown wheel thereby to bring the stop finger 15 into engagement with the intermeshing teeth of the crown wheel and ratchet wheel,

as shown in Figs. 1 and 2. This finger 15 will thus act as a stop to prevent further backward movement of the ratchet wheel.

When the main spring is wound and the crown wheel is turned in the direction of the 'ment with the ratchet wheel.

arrow 5, Fig.3,1then the friction between the crown wheel and the stop member will move the stop member with the crown wheel, thus carrying the stop finger out of engage- Suitable means hereinafter described are employed to limit the forward movement of the stop the latter will simply turn forwardly on and member, and when the stop member reaches its forward limit of movement, then during further forward turning of the crown wheel,

relative to the stop member-which is held from forward movement. When thewinding action ceases the tension of the main spring will tend to rotate the ratchet wheel and crown wheel backwardly, and because of the friction between the crown wheel and stop member such backward movement of the crown wheel will carry the stop member from the position shown in Fig. 3 to that of the ratchet wheel.

shown in Fig. 2 where the finger '15 comes into interlocking engagement with the teeth This movement provides the necessary recoil for the winding teeth 5. The resiliency of the extension 16 and its engagement with the teeth 5 causes the stop member to frictionally bear against the hub 18 at the point 18, the friction thus produced being sufficient to cause the stop member to be moved with the crown wheel. Another advantage of'this construction in volving the extension 16 is that a clicking noise will be produced as each tooth 5 wipes by the inturned end 17 of the extension, so

that the winding of the watch is accompanied by the. usual clicking noise of a stop pawl or click.

Any suitable means may be provided for limiting the turning movement of the stop ring 20 adapted to encircle the hub 13 of the crown wheel and having suflicient resiliency so that the friction between the split ring and said hub will tend to cause the stop member to rotatewith the crown wheel. This member is provided with the finger 14 having the upturned portion 15 which is situated to, have interlocking engagement with the intermeshing teethof the ratchet wheel and crown wheel as above described.

In this embodiment of the invention the necessary frictional engagement between the stop member and the crown wheel is secured by the fact that the stop member is split and has sufficient resiliency to cause it to hug the hub of the crown wheel. 7

The stop member is shown as provided on its inner edge with the notches or recesses 21, and the plate 9 is formed with projections 22 which enter these notches, the pro jections being considerably smaller than the recesses. These projections serve as limiting means for limiting the rotative-movement of the stop member when the watch is being wound.

In Figs. 8 and 9 I have shown the stop member 23 as made of a split fiat ring which has a slight spiral formation and with this construction the necessary friction between the stop member and the crown wheel is secured partly by the factthat the stop member is split and thereforetends to hug the hub 13 of the crown wheel, and partly by the spiral formation of the stop member which causes said stop. member to have frictional engagement with the under face of the crown wheel. The forward turning of the stop member23 may be limited by a shoulder such as the shoulder 19 in Figs. 1, 2 and 3.

In Fig. 10 I have shown another embodiment of the invention wherein the stop member is in the form of a resilient wire 24 of a shape to encircle and have frictional engagement with the hub 13. One end of the wire is bent downwardly to form the finger 26 which operates in a slot or groove 27 formed in the plate 9, and the other end of the wire is bent to form the stop finger 15. The frictional engagement between the resilient wire and the hub 13 will tend to cause the stop member to turn with the crown wheel and the groove 27 and finger 26 to serve as means to limit the turning movement.

In all of the embodiments of the invention the stop member has sufficient frictional engagement with the crown wheel so that the turning movement of the crown wheel in either direction will tend to turn the stop member, and the latter is provided with the stop finger which is brought into engagement with the intermeshing teeth of the crown wheel and ratchet wheel by the backward movement of the crown wheel when the winding operation ceases thereby to lock the ratchet wheel from further backward movement.

Further, in all embodiments of the invention suitable means are provided for limiting the forward movement of the stop member when the crown wheel is rotated forwardly, and the amount which the stop member is permitted to move in a forward direction determines the amount of recoil which is allowed after the winding operation stops.

In Figs. 1 to 10 the stop member is shown as assoclated with the crown wheel, but so far as the invention is concerned, the stop member might equally well be associated with the ratchet wheel 6, and in Fig. 12 I have illustrated this construction.

I claim:

In a watch, the combination with aplate having a crown-wheel-receiving recess, of a crown wheel rotatably mounted in the recess, a ratchet wheel meshing with the crown wheel, a stop member interposed between the crown wheel and the bottom of the recess and havingsuflicient frictional engagement with the crown wheel to beturned thereby as the wheel rotates, said stop member permitting free rotation of said wheel in a forward direction, and being provided with an arm situated to be carried into en gagement with the intermeshing teeth of said wheels at their point of intermeshin by a backward rotation of the crown whee In testimony whereof, I have signed my name to this specification. V

KNUT S. CARLSTROM. 

